1. Field of the Invention
The present invention generally concerns self-supporting, molded construction forms used in the building industry.
The present invention particularly concerns building forms made from a large sheets of low-density plastic or polymeric material, often polyurethane or polystyrene, that are held in a spaced-parallel relationship by metal connecting members which are commonly made from steel. Cavities of the plastic and steel forms so assembled are filled with wet concrete. After the concrete is cured, the forms become a permanent part of the building's walls.
2. Description of the Prior Art
2.1 State of the Prior Art
Construction forms have been manufactured from polymeric material, often polyurethane or polystyrene, which expands within a mold to yield a rigid, low-density, foamed plastic forms. The forms typically have a tongue and groove arrangement on all sides to permit identical forms to be placed on either side, above, or below a one form. Extended vertical and/or horizontal cavities are created between adjacent forms. Diverse items from reinforcing steel rod (re-bar) to conduit may be passed lengthwise into these cavities, and even brought to the surfaces of the forms as desired. The cavities are filled with wet concrete, forming walls of contiguous concrete. The forms are left in place, instead of being removed, when the concrete cures. In this manner the forms are supported by, as well as supporting of, the concrete, and serve as insulation to the walls of the completed building structure.
One important problem with such forms has previously been solved. This problem is the necessity of providing mechanical support for finished material such as furring strips, paneling, wall board, etc. attached to a wall that is formed by use of the forms. One early concrete form solving this problem is shown in U.S. Pat. No. 4,223,501 for a CONCRETE FORM to DeLozier. The DeLozier concrete form has been sold commercially since approximately Sep. 23, 1980; the issuance date of the DeLozier patent. In the DeLozier concrete form, sidewalls of foam polymeric material are connected by transverse connecting members. The connecting members have and present at each of their ends a lip that is parallel to the surface of the wall, and that is suitable to engage a sheet metal screw.
In their preferred form, each connecting member of the DeLozier concrete form is preferably made from a single piece of sheet material, preferably from cold rolled steel. A central connecting web portion extends between, and is embedded within, sidewall members of the form. First and second imperforate flat attachment flange portions extend perpendicularly from the web portion, and parallel to the sidewalls. These flanges are embedded within the outer surfaces of the sidewall members. In this location they may receive and support fasteners, typically screws, that penetrate the polymeric material of the sidewall members.
A purported improvement to the DeLozier concrete form is taught in U.S. Pat. No. 4,879,855 for an ATTACHMENT AND REINFORCEMENT MEMBER FOR MOLDED CONSTRUCTION FORMS to Berrenberg. In the Berrenberg form the attachment and reinforcement member of a DeLozier-type concrete form has as its central portion expanded web steel. The end portions of this member are bent and fitted with covering strips of solid galvanized steel. The web and galvanized steel are embedded within a construction form during the manufacture of the form. The strips of the solid galvanized steel extend to, and appear, on the outer surfaces of the form. They therein provide attachment services to which any standard type of wall covering such as sheet rock, siding, paneling, lath for stucco, or brick veneer may be attached. These attachment strips are spaced at regular predetermined intervals. They also define the locations of (i) any vertical cavities and/or concrete posts embedded within the wall that is formed by the construction form, and/or (ii) any conduit or other channel material previously placed within the void of the form before the pouring of the concrete wall.
Important to the DeLozier and Berrenberg forms, and to all forms of this nature, the interior of the forms must have and present an array of relatively large openings to permit the ready flow of liquid concrete vertically through several arrayed forms, therein so as to ultimately provide a continuous concrete wall (in which the wall the connecting members are embedded, and to which wall the polymeric material forms the exterior sidewalls). Although the exterior surfaces of the forms are flat, as best suits their function as wall surfaces, the interior surfaces of the DeLozier, Berrenberg and other, like, forms are very complex. The forms produce a concrete wall that, if the polymeric material were to be somehow removed, would have the substantial appearance and surface texture of a waffle. The wall, and a waffle, are in the substantial structure of a grid surface with regular high and low (thick and thin) regions, and with somewhat smoothed undulations between regions. If the polymeric material were to chiseled or scraped off a completed wall, then an undulating concrete surface in an imperforate web pattern would be exposed.
Although the exact nature of the pattern of this concrete surface is not particularly important, it is obviously beneficial that the concrete of the wall should have both (i) no excessively thin or weak points, and (ii) no long straight lines long which the wall material is uniformly thin. In other words, it is not adverse that a common edible waffle should have fracture lines, or at least lines along which relatively thinner material of the waffle may be cut with a fork or knife. However, it is not desirable that a concrete wall should have such "fracture lines". The surface of the concrete wall (as is hidden, and rendered flat, by the polymeric material) would better have the topology of the dimpled surface of a golf ball (rendered planar), or even the traditional smooth surface, than it would the surface of a waffle or cracker that is intended to fracture and to break along pre-existing fracture lines.
The interior voids of the DeLozier, Berrenberg and like forms, and the thickness of the concrete walls produced with these forms, basically vary in thickness over the scale of one connecting member to the next so that this interior void, and the interior surfaces of the form, will well support the full and free flow of concrete into every nook and cranny of the void. However, it is detrimental that the wall defined by the concrete form should vary in thickness over this scale. A wall that has relatively weaker, and relatively stronger, regions does not make the best and more efficient use of the concrete material, because the wall will always fracture at its weakest point, and along its weakest fracture line. One thing that should be avoided--if at all possible consistent with the necessity to flow concrete into the form--are long straight lines of relatively thinner thickness in the resulting concrete wall. These lines are obviously potential fracture sites, and crack lines, in the concrete wall.
Analysis of both the interior of the form and the resulting pattern of the wall that the form with regard to making both the best and strongest possible use of the available construction material (concrete) quickly leads back to the classic smooth-surface, flat, concrete wall. This classic wall--which is readily formed with traditional, normal, planar, concrete forms of wood of the like--has not been producible with the concrete forms of DeLozier and Berrenberg. The present invention will produce the classical smooth, flat concrete wall--only sheathed both sides with polymeric material. This will be the case nonetheless that (i) the polymeric material is strongly permanently attached to the interior concrete, and (ii) the poured concrete from which the wall is made has flowed reliably and well into all voids of the arrayed forms.
If an interior concrete wall made by forms of the present invention was to be, nonetheless to being superior to the "waffle-like" (interior) concrete walls made by the prior art integrating forms of DeLozier and Berrenberg, only as good at stopping cracks and fractures as is the classic, and classically constructed, smooth concrete wall, then the previous four paragraphs might amount to ado about very little. However, a wall made with factory-produced forms in accordance with the present invention will be seen not to be required to be substantially (i) straight and/or (ii) smooth, and may easily and intentionally incorporate diverse complex features of almost any desired nature--instead of the incidental and unintentional, generally undesired features, of the DeLozier and Berrenberg forms.
What might these features be? In the first place, the possible features, and the possible complexity of construction, of walls exist at many scales. Laid-up brick walls and architecture commonly do not much look like concrete walls at large scales on the order of tens of meters, the brick walls being generally more convolute. The convolutions help to stop the propagation of failures at large dimensional scales. Concrete walls and buildings are generally more plain. The forms of the present invention will be seen to permit concrete walls to be easily constructed with many more corners and angles than heretofore, adding strength as well as beauty.
At a smaller scale on the order of meters, the present invention will as show that there are features, generally exotic in nature in that they can be in the form of complex curves, that may desirably be placed in the surface, and in the thickness, of a concrete wall in order to deflect, and to stop, long cracks. These features can be complimentary to, and interactive with, reinforcing re-bar contained within the wall. These features, and these combinations, have not heretofore been seen because they would be prohibitively expensive to produce in a normal concrete wall.
Other important problems with existing forms remain. First, the leading DeLozier and Berrenberg forms are not particularly economical of fabrication. Each form must be individually molded. This is normally done by a custom fabricator, i.e., a fabricator of construction forms, and not by a plastic materials manufacturer. In other words, the sophisticated forms look nothing like any structure in which plastic material is commonly sold in bulk.
It would correspondingly be useful if construction forms could somehow be made from structures, such as plastic sheet and panel, in which plastic material is commonly delivered by plastics manufacturers with no, or minimal, re-work, and wastage.
Second, the connecting members between the sides of the forms are fairly sophisticated with multiple angles, and must be formed prior to be embedded in the form as molded. They must be held in position as the form is molded, and while it cures, and may thus negatively impact the rapidity with which the form molds may be cycled. The connecting members are not particularly economical of fabrication, and typically waste a good deal of material, which wastage may typically be galvanized steel sheet. Indeed, one of the purported advantages of the Berrenberg form is the usage of expanded webbed steel in the center of the form, alleviating a need for galvanized steel sheet throughout.
Accordingly, it would be useful if the metal connecting members of any form were of minimal material cost, simply constructed, and produced with no, or minimal, wastage of metal.
Third, the prior art DeLozier and Berrenberg forms are not particularly economical to ship. They basically serve to enclose a lot of air, which magnifies the volume of shipment. Because of the typically considerable volume of a building's walls that the forms serve to initially define, and ultimately sheath, it is usually not possible to carry all the forms for a modest size concrete building on even the largest truck. Necessary multiple deliveries of forms not only magnify costs but can cause logistical, and staging, problems when not all forms are available to place in position before the pouring of any concrete.
Accordingly, it would be useful if building forms could somehow be made more compact for shipment.
Fourth, the leading prior art molded forms permit highly efficient construction of concrete walls and buildings, but have strong competition. The molded forms permit the layout of sophisticated multi-angled and multi-cornered architecturally-interesting walls. They are amendable to the location of windows and doors. However, many concrete wall buildings--especially the more utilitarian buildings such as warehouses--typically have long expanses of plain wall. The walls are often constructed between reusable forms laid flat upon the ground, and are then hoisted into position and connected one huge wall section to the next. This very efficient modern method of concrete wall and building construction is equally, or more, cost effective than existing molded concrete forms.
If existing concrete forms are not of optimal size, and are generally too small for hugely fast and efficient wall construction, then what would an optimal large size be? And what limitations are encountered in creating and using a form of such a larger size?
In the first place, existing molded forms are not particularly large, and are generally of a size approximately four feet by one and one-half feet by 1 feet (4'.times.11/2'.times.1'), because any larger molds necessary to make such forms larger become exceedingly expensive. Next, and although a workman could seemingly lift and position something larger than the existing molded forms, there is a limit upon how large a form may become and still be practically and conveniently manipulated by a building construction worker. Finally, if and as the forms grow ever larger, then they sacrifice the flexibility of being readily adaptable to the smaller features of the building, and become difficult and time-consuming to customize to the necessary corners, and door and window openings, of the building.
Logically, it would probably be a good idea if a family of interlocking and interconnecting forms of various sizes were to be available, and/or some way would exist to spit an existing large form into compatible smaller forms. This seems difficult, however. Any proliferation of form types could multiply costs, and logistical complexity. Because the forms must have some innate strength, it does not seem immediately obvious how a form that must "hold together" when large can easily be divided into parts that are uniformly structurally sound.
Any system that would solve the challenge of producing concrete walls efficiently at both large and small scales, and with both great and small differentiation and sophistication in the walls produced, would be useful.
Fifth, and finally, existing molded concrete forms lack any capacity to be scaled in the thickness of the wall produced. A given form produces a wall of a predetermined thickness. In the real world, however, concrete walls desirably vary in thickness for many reasons. Some walls may be upon different stories of a building, with upper story walls being generally thinner than the lower story walls (and vice versa). Load-bearing walls are desirably thicker; non-load-bearing walls are desirably thinner. Walls subject to seismic stress, or in certain alignments, may suitably be thicker than other walls.
Accordingly, it would be useful if a single system of concrete forms could be used to produce, at different times and in different configurations, concrete walls of varying thickness.
2.2 Previous Patents
In greater detail, the aforementioned U.S. Pat. No. 4,223,501 to DeLozier issued Sep. 23, 1980 for a CONCRETE FORM concerns a self-supporting concrete form of foamed polymeric material. A one piece transverse connecting member is provided which mechanically holds fastening members inserted into the form, thereby providing mechanical support for finish material such as furring strips, paneling, etc. The connecting member is formed from one piece of sheet material, preferably cold rolled steel, and comprises a central connecting web portion extending between and embedded in sidewall members of the form, and first and second imperforate flat attachment flange portions extending perpendicularly from the web portion and embedded near the outer surfaces of the sidewall members for receiving and supporting fastening members penetrating the sidewall members. The web portion of the connecting member comprises an array of relatively large openings to permit the flow of concrete through the form units and to provide a high strength web of metal. The connecting members may be arranged in each form unit with one connecting member midway between the longitudinal center and each end of the form unit so that, when the form units are laid up in courses in a staggered array, the connecting members of form units in succeeding courses are aligned.
Also in greater detail, the aforementioned U.S. Pat. No. 4,879,855 to Berrenberg issued Nov. 14, 1989 for an ATTACHMENT AND REINFORCEMENT MEMBER FOR MOLDED CONSTRUCTION FORMS concerns an attachment and reinforcement member for molded construction forms that has a central portion of expanded webbed steel in which the ends are bent to accommodate covering strips of solid galvanized steel. The Berrenberg invention is embedded in a molded construction form during the form's manufacture. The strips of the solid galvanized steel extend to the outer surfaces of the form and provide attachment surfaces whereas the central portion of expanded steel web reinforces the form. The result is a molded construction form that is stronger, and one that further provides easily located embedded attachment surfaces for bracing means during the curing of the concrete and for finishing materials. The molded construction form has a number of galvanized steel strips, preferably ten with five on each outer surface, located at the standard building twelve inch centers, to provide surfaces for attaching any type of wall covering such as sheetrock, siding, paneling, lath for stucco, or brick veneer. These attachment strips also define the location of the vertical cavities and concrete posts within the construction form.
Also if relevance to aspects of the present invention is U.S. Pat. No. 4,854,097 to Haener issued Aug. 8, 1989 for INSULATED INTERLOCKING BUILDING BLOCKS concerning a building block having improved insulating characteristics. The block includes two spaced parallel sidewalls formed from concrete or the like. The first sidewall has at least one inwardly extending integral web, having end portions extending parallel to the sidewall. The second sidewall has inwardly extending interlock members which also have end portions extending parallel to the sidewall. When the sidewalls are assembled parallel to each other to form the front and back faces of the building block, the respective end portions overlap in a manner preventing the sidewalls from moving apart along a line perpendicular to the sidewalls. The overlapping end portions are not in contact with each other. At least part of the volume within the block is filled with a highly insulating foam. The foam fills the space between the overlapping end portions and thus provides structural rigidity to the block. The block has outstanding insulating properties since there are no thermal bridges of block structural material from one sidewall to the other. In the event of fire which melts or destroys the foam material, general structural integrity of a wall built from these blocks is assured by the overlapping end portions which prevent separation of the sidewalls.
U.S. Pat. No. 5,390,459 to Mensen issued Feb. 21, 1995 for CONCRETE FORM WALLS concerns a building component comprising first and second high density foam panels each having inner and outer surfaces, top and bottom, and first and second ends. The panels are arranged in spaced parallel relationship with their inner surfaces facing each other, with at least two bridging members extending between and through and molded into the panel members. Each bridging member comprises a pair of elongated end plates oriented in the top to bottom direction of the panels and abutting against the outer surfaces of the panels, and at least one web member extending between and rigidly connected to the end plates, each web member oriented in the top to bottom direction of the panels and having a height substantially less than the height of the panels.
U.S. Pat. No. 5,465,542 to Terry issued Nov. 14, 1995 for INTERBLOCKING CONCRETE FORM MODULES (SIC) concerns interlocking concrete form modules suitable for creating a concrete wall form. The modules have the general shape of a right rectangular parallelepiped with parallel side walls joined by integral webs that define a plurality of parallel elongate cavities. The edges of the side walls include tongues and grooves that allow the modules to be interlocked to form a wall. The ends of the webs are undercut such that cavities between the modules are created when the modules are suitably interlocked. The between-the-module cavities lie orthogonal to the through-the-module cavities. The modules are formed of an insulating material and left in place. Preferably, the tongues along one edge include notches aligned with the webs. In one embodiment, the modules substantially entirely are formed of relatively dense (3-5 lb./ft..sup.3) expanded polystyrene (EPS). The density of the EPS is adequate to hold threaded wall anchors. In an alternate embodiment, the modules are formed of less dense (approximately 1.5 lb./ft..sup.3) EPS and include embedded nonmetallic attachment elements that are sized and positioned such that surfaces of the attachment elements lie co-planar with the outer surfaces of the side walls of the modules. Preferably, the nonmetallic attachment elements span substantially the entire height of the modules to create equi-spaced furring strips that cover substantially the entire height of a wall formed when the modules are suitably assembled.
U.S. Pat. No. 5,456,444 to Wegman issued Oct. 10, 1995 for CONCRETE FORM WALL ASSEMBLIES AND METHODS concerns a wall form assembly in which a pair of form wall assemblies are kept in preselected spaced parallel relationship by means of cross members fitted within end slots and interlocked by means of pins with elongate braces mounted for movement from a low profile position for transport to a high profile operative position in which the width dimension is transverse to the plane of the form wall for maximum resistance to bowing from the hydrostatic forces of wet cement.
U.S. Pat. No. 4,646,496 to Wilnau issued Mar. 3, 1987 for STRUCTURAL WALL AND CONCRETE FORM SYSTEM concerns a combined structural wall and concrete form system, and form bracket apparatus in which a wall frame acts as the side walls of a poured concrete form, while supporting the form in place. A plurality of brackets are transversely attached to the wall frame adjacent the position of the column form to support form ties for locking the remaining form walls in place to complete a concrete column form and structural wall combination. The header of the wall frame portion acts as the bottom wall of a concrete beam form, while the same brackets as used for the column form can be attached along the top portion of the wall frame for locking beam forms and form ties in place to support the side walls of the concrete beam form. A top bracket formed with angle iron and straps supports the top portion of the side walls of the beam form. The form support brackets are elongated flat metal members of predetermined length having a plurality of slots therein for driving nails and having alignment notches positioned therein, along with upright form support end portions having an angled edge for driving form ties in place. The brackets are adapted for supporting the form ties for both the columns and beams when used in connection with the wall frame.
U.S. Pat. No. 4,443,981 to Weiss issued Apr. 24, 1984 for CONCRETE FORM SYSTEM concerns a system for pouring concrete and thereby forming concrete floors, sidewalks and the like, wherein the forms used to retain the concrete in place remain as part of the permanent installation. The system is constructed basically of longitudinal rails, stakes and clips which fit snugly and securely together to form concrete retaining forms.